/* OggSharp
 * Copyright (C) 2000 ymnk, JCraft,Inc.
 *  
 * Written by: 2000 ymnk<ymnk@jcraft.com>
 * Ported to C# from JOrbis by: Mark Crichton <crichton@gimp.org> 
 *   
 * Thanks go to the JOrbis team, for licencing the code under the
 * LGPL, making my job a lot easier.
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License
 * as published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
   
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


using System;


namespace OggSharp 
{
	class Lookup
	{
		static int COS_LOOKUP_SZ=128;
		static float[] COS_LOOKUP={
									  +1.0000000000000f,+0.9996988186962f,+0.9987954562052f,+0.9972904566787f,
									  +0.9951847266722f,+0.9924795345987f,+0.9891765099648f,+0.9852776423889f,
									  +0.9807852804032f,+0.9757021300385f,+0.9700312531945f,+0.9637760657954f,
									  +0.9569403357322f,+0.9495281805930f,+0.9415440651830f,+0.9329927988347f,
									  +0.9238795325113f,+0.9142097557035f,+0.9039892931234f,+0.8932243011955f,
									  +0.8819212643484f,+0.8700869911087f,+0.8577286100003f,+0.8448535652497f,
									  +0.8314696123025f,+0.8175848131516f,+0.8032075314806f,+0.7883464276266f,
									  +0.7730104533627f,+0.7572088465065f,+0.7409511253550f,+0.7242470829515f,
									  +0.7071067811865f,+0.6895405447371f,+0.6715589548470f,+0.6531728429538f,
									  +0.6343932841636f,+0.6152315905806f,+0.5956993044924f,+0.5758081914178f,
									  +0.5555702330196f,+0.5349976198871f,+0.5141027441932f,+0.4928981922298f,
									  +0.4713967368260f,+0.4496113296546f,+0.4275550934303f,+0.4052413140050f,
									  +0.3826834323651f,+0.3598950365350f,+0.3368898533922f,+0.3136817403989f,
									  +0.2902846772545f,+0.2667127574749f,+0.2429801799033f,+0.2191012401569f,
									  +0.1950903220161f,+0.1709618887603f,+0.1467304744554f,+0.1224106751992f,
									  +0.0980171403296f,+0.0735645635997f,+0.0490676743274f,+0.0245412285229f,
									  +0.0000000000000f,-0.0245412285229f,-0.0490676743274f,-0.0735645635997f,
									  -0.0980171403296f,-0.1224106751992f,-0.1467304744554f,-0.1709618887603f,
									  -0.1950903220161f,-0.2191012401569f,-0.2429801799033f,-0.2667127574749f,
									  -0.2902846772545f,-0.3136817403989f,-0.3368898533922f,-0.3598950365350f,
									  -0.3826834323651f,-0.4052413140050f,-0.4275550934303f,-0.4496113296546f,
									  -0.4713967368260f,-0.4928981922298f,-0.5141027441932f,-0.5349976198871f,
									  -0.5555702330196f,-0.5758081914178f,-0.5956993044924f,-0.6152315905806f,
									  -0.6343932841636f,-0.6531728429538f,-0.6715589548470f,-0.6895405447371f,
									  -0.7071067811865f,-0.7242470829515f,-0.7409511253550f,-0.7572088465065f,
									  -0.7730104533627f,-0.7883464276266f,-0.8032075314806f,-0.8175848131516f,
									  -0.8314696123025f,-0.8448535652497f,-0.8577286100003f,-0.8700869911087f,
									  -0.8819212643484f,-0.8932243011955f,-0.9039892931234f,-0.9142097557035f,
									  -0.9238795325113f,-0.9329927988347f,-0.9415440651830f,-0.9495281805930f,
									  -0.9569403357322f,-0.9637760657954f,-0.9700312531945f,-0.9757021300385f,
									  -0.9807852804032f,-0.9852776423889f,-0.9891765099648f,-0.9924795345987f,
									  -0.9951847266722f,-0.9972904566787f,-0.9987954562052f,-0.9996988186962f,
									  -1.0000000000000f,
		};
		/* interpolated lookup based cos function, domain 0 to PI only */
		internal static float coslook(float a)
		{
			double d=a*(.31830989*(float)COS_LOOKUP_SZ);
			int i=(int)d;
			return COS_LOOKUP[i]+ ((float)(d-i))*(COS_LOOKUP[i+1]-COS_LOOKUP[i]);
		}     

		static int INVSQ_LOOKUP_SZ=32;
		static float[] INVSQ_LOOKUP={
										1.414213562373f,1.392621247646f,1.371988681140f,1.352246807566f,
										1.333333333333f,1.315191898443f,1.297771369046f,1.281025230441f,
										1.264911064067f,1.249390095109f,1.234426799697f,1.219988562661f,
										1.206045378311f,1.192569588000f,1.179535649239f,1.166919931983f,
										1.154700538379f,1.142857142857f,1.131370849898f,1.120224067222f,
										1.109400392450f,1.098884511590f,1.088662107904f,1.078719779941f,
										1.069044967650f,1.059625885652f,1.050451462878f,1.041511287847f,
										1.032795558989f,1.024295039463f,1.016001016002f,1.007905261358f,
										1.000000000000f,
		};
		/* interpolated 1./sqrt(p) where .5 <= p < 1. */
		internal static float invsqlook(float a)
		{
			// System.out.println(a);
			double d=a*(2.0f*(float)INVSQ_LOOKUP_SZ)-(float)INVSQ_LOOKUP_SZ;
			int i=(int)d;
			return INVSQ_LOOKUP[i]+ ((float)(d-i))*(INVSQ_LOOKUP[i+1]-INVSQ_LOOKUP[i]);
		}

		static int INVSQ2EXP_LOOKUP_MIN=-32;
		//static int INVSQ2EXP_LOOKUP_MAX=32;
		static float[] INVSQ2EXP_LOOKUP={
											65536.0f,    46340.95001f,        32768.0f,    23170.47501f,
											16384.0f,     11585.2375f,         8192.0f,    5792.618751f,
											4096.0f,    2896.309376f,         2048.0f,    1448.154688f,
											1024.0f,    724.0773439f,          512.0f,     362.038672f,
											256.0f,     181.019336f,          128.0f,    90.50966799f,
											64.0f,      45.254834f,           32.0f,      22.627417f,
											16.0f,     11.3137085f,            8.0f,    5.656854249f,
											4.0f,    2.828427125f,            2.0f,    1.414213562f,
											1.0f,   0.7071067812f,            0.5f,   0.3535533906f,
											0.25f,   0.1767766953f,          0.125f,  0.08838834765f,
											0.0625f,  0.04419417382f,        0.03125f,  0.02209708691f,
											0.015625f,  0.01104854346f,      0.0078125f, 0.005524271728f,
											0.00390625f, 0.002762135864f,    0.001953125f, 0.001381067932f,
											0.0009765625f, 0.000690533966f,  0.00048828125f, 0.000345266983f,
											0.000244140625f,0.0001726334915f,0.0001220703125f,8.631674575e-05f,
											6.103515625e-05f,4.315837288e-05f,3.051757812e-05f,2.157918644e-05f,
											1.525878906e-05f,
		};
		/* interpolated 1./sqrt(p) where .5 <= p < 1. */
		internal static float invsq2explook(int a)
		{
			return INVSQ2EXP_LOOKUP[a-INVSQ2EXP_LOOKUP_MIN];
		}

		const int FROMdB_LOOKUP_SZ=35;
		const int FROMdB2_LOOKUP_SZ=32;
		const int FROMdB_SHIFT=5;
		const int FROMdB2_SHIFT=3;
		const int FROMdB2_MASK=31;
		static float[] FROMdB_LOOKUP = {
										   1.0f,   0.6309573445f,   0.3981071706f,   0.2511886432f,
										   0.1584893192f,            0.1f,  0.06309573445f,  0.03981071706f,
										   0.02511886432f,  0.01584893192f,           0.01f, 0.006309573445f,
										   0.003981071706f, 0.002511886432f, 0.001584893192f,          0.001f,
										   0.0006309573445f,0.0003981071706f,0.0002511886432f,0.0001584893192f,
										   0.0001f,6.309573445e-05f,3.981071706e-05f,2.511886432e-05f,
										   1.584893192e-05f,          1e-05f,6.309573445e-06f,3.981071706e-06f,
										   2.511886432e-06f,1.584893192e-06f,          1e-06f,6.309573445e-07f,
										   3.981071706e-07f,2.511886432e-07f,1.584893192e-07f,
		};
		static float[] FROMdB2_LOOKUP = {
											0.9928302478f,   0.9786445908f,   0.9646616199f,   0.9508784391f,
											0.9372921937f,     0.92390007f,   0.9106992942f,   0.8976871324f,
											0.8848608897f,   0.8722179097f,   0.8597555737f,   0.8474713009f,
											0.835362547f,    0.8234268041f,   0.8116616003f,   0.8000644989f,
											0.7886330981f,   0.7773650302f,   0.7662579617f,    0.755309592f,
											0.7445176537f,   0.7338799116f,   0.7233941627f,   0.7130582353f,
											0.7028699885f,   0.6928273125f,   0.6829281272f,   0.6731703824f,
											0.6635520573f,   0.6540711597f,   0.6447257262f,   0.6355138211f,
		};
		/* interpolated lookup based fromdB function, domain -140dB to 0dB only */
		internal static float fromdBlook(float a)
		{
			int i=(int)(a*((float)(-(1<<FROMdB2_SHIFT))));
			return (i<0)?1.0f:
				((i>=(FROMdB_LOOKUP_SZ<<FROMdB_SHIFT))?0.0f:
				FROMdB_LOOKUP[(uint)i>>FROMdB_SHIFT]*FROMdB2_LOOKUP[i&FROMdB2_MASK]);
		}

	}
}
